NPY peptide analogs

ABSTRACT

Human Neuropeptide Y(NPY) has the formula: H-Tyr-Pro-Ser-Lys-Pro-Asp-Asn-Pro-Gly-Glu-Asp-Ala- Pro-Ala-Glu-Asp-Met-Ala-Arg-Tyr-Tyr-Ser-Ala-Leu-Arg-His-Tyr- Ile-Asn-Leu-Ile-Thr-Arg-Gln-Arg-Tyr-NH 2 . Porcine and rat NPY have the same sequence except for Leu instead of Met in the 17-position. Porcine PYY is homologous having 11 different residues. NPY analogs wherein the N-terminus is shortened and which may contain one or more specific subsitutions for the naturally occurring residues, or pharmaceutically acceptable salts thereof, dispersed in a pharmaceutically acceptable liquid or solid carrier, can be administered to mammals, including humans, to substantially lower blood pressure over an extended period of time or to counteract hypertension.

This invention was made with Government support under Grants AM-26741and HL-37716 awarded by the National Institutes of Health. TheGovernment has certain rights in this invention.

This invention is generally directed to Neuropeptide Y(NPY) and tomethods for pharmaceutical treatment of mammals using analogs of such apeptide. More specifically, the invention relates to NPY analogs, topharmaceutical compositions containing such peptides and to methods oftreatment of mammals using such peptides to lower blood pressure.

BACKGROUND OF THE INVENTION

Experimental and clinical observations have supported the concept thatneuropeptides play central roles in neurotransmission as well as theregulation of secretory functions of adenohypophysial, pancreatic,adrenalcortical and gut cells. Among the thirty or so neuropeptides thathave been implicated in neuronal function in the mammalian centralnervous system, several have also been suggested to function asneurotransmitters or neuromodulators primarily in afferent neurons.

NPY is a 36-residue, amidated peptide hormone which was first isolatedfrom porcine brain and characterized. NPY is anatomically co-distributedand co-released with norepinephrine in and from sympatheticpostganglionic neurons. Stimulation of the sympathetic nervous systemunder physiologic circumstances, e.g. exercise, cold exposure, surgicalstress, etc., promotes an elevation of plasma concentrations of NPY. NPYis believed to participate along with norepinephrine in the regulationof vascular smooth muscle tone and maintenance of blood pressure. Inaddition to the post-synaptic action to increase vascular smooth muscletone, NPY may also act presynaptically to inhibit both its own releaseand that of norepinephrine. This mechanism is similar to the presynapticactions of norepinephrine that, acting through α₂ -adrenoreceptors,facilitates a local feedback regulation of the neurohumoral regulationof blood pressure. Over the past 30 years, knowledge of norepinephrine'srole in regulation of blood pressure has resulted in increasing ourunderstanding of cardiovascular regulation and the successfuldevelopment of a variety of pharmacotherapeutic substances usedclinically to treat disorders of cardiovascular function. Thesecompounds are, in general, structural analogs of norepinephrine andserve as either agonists or antagonists of norepinephrine to treathypotension or hypertension, respectively. These drugs, however useful,have not solved the problems of management of a variety ofcardiovascular disorders.

An additional action of NPY is to decrease cardiac contractility(inotropy). This is an extremely important action of NPY, because it isknown that, under many circumstances in which inotropy is decreased,diseases of life-threatening importance, e.g. congestive heart failureand cardiogenic shock, are associated with probable increased release ofNPY into the blood. Prevention of NPY release, using a presynaptic NPYagonist, or NPY's action, using a postsynaptic NPY antagonist, may bebeneficial in these disease states.

NPY has also been reported to produce coronary artery vasoconstrictionand thereby may decrease myocardial blood flow resulting in myocardialischemia. Such a circumstance can result in angina pectoris or, undermore severe circumstances, may result in myocardial infarction anddeath. In recent years, several classes of drugs have proven effectivein dilating coronary arteries to prevent such events. The use of analogsof NPY are expected to prove useful in treatment of such problems.

Porcine NPY has the formula:H-Tyr-Pro-Ser-Lys-Pro-Asp-Asn-Pro-Gly-Glu-Asp-Ala-Pro-Ala-Glu-Asp-Leu-Ala-Arg-Tyr-Tyr-Ser-Ala-Leu-Arg-His-Tyr-Ile-Asn-Leu-Ile-Thr-Arg-Gln-Arg-Tyr-NH.sub.2.The formula of Human NPY has been deduced from clones obtained fromtotal RNA by preparing cDNA and then employing DNA sequencingtechnologies and is accepted to be:H-Tyr-Pro-Ser-Lys-Pro-Asp-Asn-Pro-Gly-Glu-Asp-Ala-Pro-Ala-Glu-Asp-Met-Ala-Arg-Tyr-Tyr-Ser-Ala-Leu-Arg-His-Tyr-Ile-Asn-Leu-Ile-Thr-Arg-Gln-Arg-Tyr-NH.sub.2.

SUMMARY OF THE INVENTION

NPY has a wide range of biological actions including cardiovasculareffects such as increasing mean arterial pressure (MAP) when injectedinto conscious rats. NPY analogs which are shortened at the N-terminusand which may have substitutions at certain other positions in the chainsubstantially decrease the MAP. The invention provides peptides from 18-to 20-residues in length, hereinafter termed NPY analogs, having theformula: X-Q-R₁₉ -R₂₀ -R₂₁ -R₂₂ -R₂₃ -Leu-R₂₅ -R₂₆ -R₂₇ -R₂₈ -R₂₉ -R₃₀-R₃₁ -R₃₂ -Arg-R₃₄ -Arg-R₃₆ -Y wherein X is H or C^(a) Me or N^(a) Me ordesamino or an acyl group having 7 carbon atoms or less; Q is R₁₇ -R₁₈,R₁₈ or desQ; R₁₇ is Met, Arg, Nle, Nva, Leu, Ala or D-Ala; R₁₈ is Ala,Ser, Ile, D-Ala, D-Ser or D-Ile; R₁₉ is Arg, Lys or Gln; R₂₀ is Tyr orPhe; R₂₁ is Tyr, Glu, His or Ala; R₂₂ is Ser, Ala, Thr, Asn or Asp; R₂₃is Ala, Asp, Glu, Gln, Asn or Ser; R₂₅ is Arg or Gln; R₂₆ is His, Arg orGln; R₂₇ is Phe or Tyr; R₂₈ is Ile, Leu, Val or Arg; R₂₉ is Asn or Ile;R₃₀ is Leu, Met, Thr or Val; R₃₁ is Ile, Val or Leu; R₃₂ is Thr or Phe;R₃₄ is Gln, Pro or His; R₃₆ is Phe or Tyr; and Y is NH₂ or OH; providedthat when Q is R₁₈, then at least one of R₂₇ and R₃₆ is Phe. Analogs ofNPY have the following applications: potent post-synaptic treatment ofhypertension and cardiogenic shock, the treatment of acutecardiovascular circulatory failure, and the elevation of intracellularcalcium.

Certain preferred NPY analogs have the formula: X-R₁₈ -Arg-Tyr-Tyr-R₂₂-R₂₃ -Leu-Arg-His-Tyr-R₂₈ -Asn-Leu-R₃₁ -Thr-Arg-Gln-Arg-Tyr-NH₂, whereinX is H or C^(a) Me or N^(a) Me or desamino or an acyl group having 7carbon atoms or less; R₁₈ is Ala or Ser; R₂₂ is Ser or Ala; R₂₃ is Alaor Ser; R₂₇ is Phe or Tyr; R₂₈ is Ile or Leu; R₃₁ is Ile or Val; and R₃₆is Phe or Tyr; provided that at least one of R₂₇ and R₃₆ is Phe.

Other preferred NPY analogs have the formula: X-R₁₇ -R₁₈-Arg-Tyr-Tyr-Ser-Ala-Leu-Arg-His-R₂₇-Ile-Asn-Leu-Ile-Thr-Arg-Gln-Arg-R₃₆ -NH₂, wherein R₁₇ is Arg or Leu andR₁₈ is Ser or Ala or Ile; and wherein X, R₂₇ and R₃₆ are as previouslyindicated.

Still other preferred NPY analogs have the formula: X-R₁₈-Arg-Tyr-Tyr-Ala-Ser-Leu-R₂₅ -His-R₂₇-Leu-Asn-Leu-Val-Thr-Arg-Gln-Arg-R₃₆ -NH₂, wherein X is desamino orC^(a) Me or N^(a) Me and wherein R₁₈, R₂₅, R₂₇ and R₃₆ are as previouslyindicated.

These synthetic peptide NPY analogs substantially lower blood pressurefor an extended time period. Pharmaceutical compositions in accordancewith the invention include NPY analogs, or nontoxic addition saltsthereof, dispersed in a pharmaceutically acceptable liquid or solidcarrier. Such peptides or pharmaceutically acceptable addition saltsthereof may be administered to mammals in accordance with the inventionfor lowering blood pressure or other regulation as described above.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The nomenclature used to define the peptides is that specified bySchroder & Lubke, "The Peptides", Academic Press (1965) wherein, inaccordance with conventional representation, the N-terminal appears tothe left and the C-terminal to the right. Where the amino acid residuehas isomeric forms, it is the L-form of the amino acid that isrepresented herein unless otherwise expressly indicated. By Nva is meantnorvaline, and by Nle is meant norleucine.

The invention provides NPY analogs having the following formula (I):X-Q-R₁₉ -R₂₀ -R₂₁ -R₂₂ -R₂₃ -Leu-R₂₅ -R.sub. 26 -R₂₇ -R₂₈ -R₂₉ -R₃₀ -R₃₁-R₃₂ -Arg-R₃₄ -Arg-R₃₆ -Y wherein X is H or C^(a) Me or N^(a) Me ordesamino or an acyl group having 7 carbon atoms or less; Q is R₁₇ -R₁₈,R₁₈ or desQ; R₁₇ is Met, Arg, Nle, Nva, Leu, Ala or D-Ala; R₁₈ is Ala,Ser, Ile, D-Ala, D-Ser or D-Ile; R₁₉ is Arg, Lys or Gln; R₂₀ is Tyr orPhe; R₂₁ is Tyr, Glu, His or Ala; R₂₂ is Ser, Ala, Thr, Asn or Asp; R₂₃is Ala, Asp, Glu, Gln, Asn or Ser; R₂₅ is Arg or Gln; R₂₆ is His, Arg orGln; R₂₇ is Phe or Tyr; R₂₈ is Ile, Leu, Val or Arg; R₂₉ is Asn or Ile;R₃₀ is Leu, Met, Thr or Val; R₃₁ is Ile, Val or Leu; R₃₂ is Thr or Phe;R₃₄ is Gln, Pro or His; R₃₆ is Phe or Tyr; and Y is NH₂ or OH; providedthat when Q is R₁₈, then at least one of R₂₇ and R₃₆ is Phe. When X isnot H, C^(a) Me, N^(a) Me or desamino, X is preferably acetyl(Ac),acrylyl(Acr), formyl(For) or benzoyl(Bz).

By C^(a) Me is meant that the amino acid residue in question, i.e. thatwhich appears at N-terminus of the peptide, has a methyl substitution onits alpha-carbon atom. By N^(a) Me is meant that the amino acid residuein question has a methyl substitution in its alpha-amino group. Bydesamino is meant that the amino acid residue at the N-terminus of thepeptide has its alpha-amino group removed and replaced by hydrogen. BydesQ is meant that the reference group "Q" is deleted so that R₁₉appears at the N-terminus of the peptide.

The peptides can be synthesized by any suitable method, such as byexclusively solid-phase techniques, by partial solid-phase techniques,by fragment condensation or by classical solution addition. SyntheticNPY analogs may also be entirely or partially synthesized by recentlydeveloped recombinant DNA techniques, which may likely be used forlarge-scale production.

For example, the techniques of exclusively solid-phase synthesis are setforth in the textbook "Solid-Phase Peptide Synthesis", Stewart & Young,Freeman & Co., San Francisco, 1969, and are exemplified by thedisclosure of U.S. Pat. No. 4,105,603, issued Aug. 8, 1978 to Vale etal. The fragment condensation method of synthesis is exemplified in U.S.Pat. No. 3,972,859 (Aug. 3, 1976). Other available syntheses areexemplified by U.S. Pat. No. 3,842,067 (Oct. 15, 1974) and U.S. Pat. No.3,862,925 (Jan. 28, 1975).

Synthesis by the use of recombinant DNA techniques, for purposes of thisapplication, should be understood to include the suitable employment ofa structural gene coding for all or an appropriate section of the NPYanalog to transform a microorganism, using an expression vectorincluding a promoter and operator together with such structural gene,and causing such transformed microorganism to express the peptide orsuch a synthetic peptide fragment. A non-human animal may also be usedto produce the peptide by gene-farming using such a structural gene inthe microinjection of embryos as described in W083/01783 published 26May 1983 and W082/0443 published 23 Dec. 1982.

Common to coupling-type chemical syntheses of peptides is the protectionof the labile side chain groups of the various amino acid moieties withsuitable protecting groups which prevent a chemical reaction fromoccurring at that site until the group is ultimately removed. Usuallyalso common is the protection of an alpha-amino group on an amino acidor a fragment while that entity reacts at the carboxyl group, followedby the selective removal of the alpha-amino protecting group to allowsubsequent reaction to take place at that location. Accordingly, it iscommon that, as a step in the synthesis, an intermediate compound isproduced which includes each of the amino acid residues located in itsdesired sequence in the peptide chain with various of these residueshaving side-chain protecting groups.

In preparing the peptides of the present invention, intermediates arecreated having the formula (II) X₁ -R₁₇ (X⁷)-R₁₈ (X³)-R₁₉ (X⁴ or X⁶ orX⁷)-R₂₀ (X²)-R₂₁ (X² or X⁵ or X⁸)-R₂₂ (X³ or X⁵ or X⁶)-R₂₃ (X³ or X⁵ orX⁶)-Leu-R₂₅ (X⁶ or X⁷)-R₂₆ (X⁶ or X⁷ or X⁸)-R₂₇ (X²)-R₂₈ (X⁷)-R₂₉(X⁶)-R₃₀ (X³)-R₃₁ R₃₂ (X³)-Arg(X⁷)-R₃₄ (X⁶ or X⁸)-Arg(X⁷)-R₃₆ (X²)-X⁹wherein the R-groups are as hereinbefore defined.

X¹ is either hydrogen or an alpha-amino protecting group and when X inthe desired peptide is a particular acyl group, that group can be usedas the protecting group. The alpha-amino protecting groups contemplatedby X¹ are those known to be useful in the art in the step-wise synthesisof polypeptides. Among the classes of alpha-amino protecting groupswhich may be urethane X used as X¹ are: (1) aromatic urethane-typeprotecting groups, such as fluorenylmethyloxycarbonyl (FMOC),benzyloxycarbonyl(Z) and substituted Z, such asp-chlorobenzyloxycarbonyl, p-nitrobenzyloxycarbonyl,p-bromobenzyloxycarbonyl, p-methoxybenzyloxycarbonyl; (2) aliphaticurethan protecting groups, such as t-butyloxycarbonyl(BOC),diisopropylmethoxycarbonyl, isopropyloxycarbonyl, ethoxycarbonyl,allyloxycarbonyl; and (3) cycloalkyl urethan-type protecting groups,such as and cyclopentyloxycarbonyl, adamantyloxycarbonyl, andcyclohexyloxycarbonyl. The preferred alpha-amino protecting group isBOC.

X² is a protecting group for the phenolic hydroxyl group of Tyr,selected from the group consisting of tetrahydropyranyl, tert-butyl,trityl, benzyl, Z, 4-bromobenzyloxycarbonyl and 2,6-dichlorobenzyl(DCB).DCB is preferred.

X³ is a protecting group for the hydroxyl group of Thr and Ser and ispreferably selected from the class consisting of acetyl(Ac),benzoyl(Bz), tert-butyl, triphenylmethyl(trityl), tetrahydropyranyl,benzyl ether(Bzl) and 2,6-dichlorobenzyl(DCB). The most preferredprotecting group is Bzl. X³ can be hydrogen, which means there is noprotecting group on the hydroxyl group.

X⁴ is hydrogen or a protecting group for the side chain amino group ofLys, such as 2-chlorobenzyloxycarbonyl(2-Cl-Z), Tos, CBZ,t-amyloxycarbonyl and BOC.

X⁵ is hydrogen or an ester-forming protecting group for the side chaincarboxyl group of Asp and Glu, preferably selected from the classconsisting of benzyl, 2,6-dichlorobenzyl, methyl, ethyl and t-butylester. OBzl is most preferred.

X⁶ is hydrogen or a protecting group for the amido group of Asn and Glnand is preferably xanthyl(Xan).

X⁷ is a protecting group for the guanido group of Arg preferablyselected from the class consisting of nitro, p-toluenesulfonyl(Tos), Z,adamantyloxycarbonyl and BOC, or is hydrogen. Tos is most preferred.

X⁸ is hydrogen or a protecting group for the imidazole nitrogen of His,such as Tos or 2,4-dinitrophenyl(DNP).

Although the side chain methylthiol group of Met can be protected byoxygen or the like, preferably Met is left unprotected.

The selection of a side chain amino protecting group is not criticalexcept that it should be one which is not removed during deprotection ofthe alpha-amino groups during the synthesis. Hence, the alpha-aminoprotecting group and the side chain amino protecting group cannot be thesame.

X⁹ may be NH₂, or an ester or amide anchoring bond used in solid phasesynthesis for linking to a solid resin support, represented by theformula:

--O--CH₂ --polystyrene resin support,

--O--CH₂ --benzyl-polyamide resin support,

--NH--benzhydrylamine (BHA) resin support, and

--NH--paramethylbenzhydrylamine (MBHA) resin support.

The polyamide polymer is commercially available and is discussed indetail in Bioorganic Chemistry, 8, 351-370 (1979) where a preferredversion of it is discussed in FIG. 6 therein. Use of BHA or MBHA resinis preferred, and cleavage directly gives the NPY analog amide.

When X is acetyl(Ac), for example, in the final formula, it may bepossible to employ it as the X¹ protecting group for the alpha-aminogroup of D-Tyr or Tyr by adding it before the coupling of this lastamino acid to the peptide chain. However, a reaction is preferablycarried out with the peptide on the resin (after deblocking thealpha-amino group while the side-chain groups remain protected), e.g. byreacting with acetic acid in the presence of dicyclohexylcarbodiimide(DCC) or preferably with acetic anhydride or by anothersuitable reaction as known in the art. Other examples of X includeacrylyl and benzoyl which could be similarly incorporated.

In the Formula (II) for the intermediate, at least one of X¹, X², X³,X⁴, X⁵, X⁶, X⁷, X⁸ and X⁹ is a protecting group or an anchoring bond.Thus, the invention also provides a method for manufacturing a peptidehaving Formula (I) by (a) first forming a peptide of Formula (II)wherein: X, X¹, X², X³, X⁴, X⁵, X⁶, X⁷, and X⁸ are each either hydrogenor a protective group and X⁹ is either a protective group or ananchoring bond to resin support or NH₂, with at least one X-group beingeither a protecting group or an anchoring bond; (b) splitting off theprotective group or groups or anchoring bond from said peptide ofFormula (II); and (c) if desired, converting a resulting peptide into anontoxic salt thereof.

In selecting a particular side chain protecting group to be used in thesynthesis of the peptides, the following rules are followed: (a) theprotecting group should be stable to the reagent and under the reactionconditions selected for removing the alpha-amino protecting group ateach step of the synthesis, (b) the protecting group should retain itsprotecting properties and not be split off under coupling conditions and(c) the side chain protecting group must be removable, upon thecompletion of the synthesis containing the desired amino acid sequence,under reaction conditions that will not alter the peptide chain.

When the peptides are not prepared using recombinant DNA technology,they are preferably prepared using solid phase synthesis, such as thatdescribed by Merrifield, J. Am. Chem. Soc., 85, p 2149 (1964), althoughother equivalent chemical syntheses known in the art can also be used aspreviously mentioned. Solid-phase synthesis is commenced from theC-terminus of the peptide by coupling a protected alpha-amino acid to asuitable resin as generally set forth in U.S. Pat. No. 4,244,946 issuedJan. 21, 1981 to Rivier et al., the disclosure of which is incorporatedherein by reference. Such a starting material for NPY analogs can, forexample, be prepared by attaching alpha-amino- and side-chain-protectedTyr to a BHA resin.

Tyr protected by BOC and DCB is coupled to the BHA resin using methylenechloride or dimethylformamide (DMF) as solvent with a suitable couplingreagent. The selection of an appropriate coupling reagent is within theskill of the art. Particularly suitable as a coupling reagent isN,N'-dicyclohexyl carbodiimide (DCC). The activating reagents used inthe solid phase synthesis of the peptides are well known in the peptideart. Examples of suitable activating reagents are carbodiimides, such asN,N'-diisopropyl carbodiimide andN-ethyl-N'-(3-dimethylaminopropyl)carbodiimide. Other activatingreagents and their use in peptide coupling are described by Schroder &Lubke, supra, in Chapter III and by Kapoor, J. Phar. Sci., 59, pp 1-27(1970).

Following the coupling of BOC-Tyr(DCB) to the resin support, thealpha-amino protecting group is removed, as by using trifluoroaceticacid(TFA) in methylene chloride, TFA alone or with HCl in dioxane.Preferably 50% TFA in methylene chloride is used with 0-5% 1,2ethanedithiol. The deprotection is carried out at a temperature betweenabout 0° C. and room temperature. Other standard cleaving reagents andconditions for removal of specific alpha-amino protecting groups may beused as described in Schroder & Lubke, "The Peptides", 1 pp 72-75(Academic Press 1965).

After removal of the alpha-amino protecting group, the remainingalpha-amino- and side-chain-protected amino acids are coupled step-wisein the desired order to obtain the intermediate compound definedhereinbefore. As an alternative to adding each amino acid separately inthe synthesis, some of them may be coupled to one another prior toaddition to the solid phase reactor. Each protected amino acid or aminoacid sequence is introduced into the solid phase reactor in about a twoto fourfold excess, and the coupling is carried out in a medium ofdimethylformamide(DMF):CH₂ Cl₂ (1:1) or in DMF or CH₂ Cl₂ alone. Ininstances where the coupling is carried out manually, the success of thecoupling reaction at each stage of the synthesis can be monitored by theninhydrin reaction, as described by E. Kaiser et al., Anal. Biochem. 34,595 (1970). In cases where incomplete coupling occurs, the couplingprocedure is repeated before removal of the alpha-amino protecting groupprior to the coupling of the next amino acid. The coupling reactions canbe performed automatically, as on a Beckman 990 automatic synthesizer,using a program such as that reported in Rivier et al., Biopolymers.1978, 17, pp 1927-1938.

After the desired amino acid sequence has been completed, theintermediate peptide is removed from the resin support by treatment witha reagent, such as liquid hydrogen fluoride, which not only cleaves thepeptide from the resin but also cleaves the alpha-amino protecting groupX¹ and all remaining side chain protecting groups X², X³, X⁴, X⁵, X⁶, X⁷and X⁸ to obtain the peptide.

The following Examples set forth preferred methods for synthesizing NPYanalogs by the solid-phase technique and generally is in accordance withthe procedure set forth in U.S. Pat. No. 4,415,558 to Vale, et al,issued Nov. 15, 1983, the disclosure of which is incorporated herein byreference.

EXAMPLE I

The synthesis of pNPY (17-36) having the formula:H-Leu-Ala-Arg-Tyr-Tyr-Ser-Ala-Leu-Arg-His-Tyr-Ile-Asn-Leu-Ile-Thr-Arg-Gln-Arg-Tyr-NH₂is conducted in a stepwise manner on a methylbenzhydrylaminehydrochloride resin, such as available from Bachem, Inc., having asubstitution range of about 0.1 to 0.5 mmoles/gm. resin. The synthesisis performed on an automatic Beckman 990B peptide synthesizer under anN₂ atmosphere. Coupling of BOC-Tyr(DCB) results in the substitution ofabout 0.35 mmol. Tyr per gram of resin. The program used is generallythat reported in Marki et al., J. Am. Chem. Soc. 103, 3178-3185 (1981).

After deprotection and neutralization, the peptide chain is builtstep-by-step on the resin. Generally, one to two mmol. of BOC-protectedamino acid in methylene chloride is used per gram of resin, plus oneequivalent of 2 molar DCCI in methylene chloride, for two hours. WhenBOC-Arg(Tos) is being coupled, a mixture of 50% DMF and methylenechloride is used. Bzl is used as the hydroxyl side-chain protectinggroup for Ser and Thr. P-nitrophenyl ester(ONp) is used to activate thecarboxyl end of Asn and Gln, and for example, BOC-Asn(ONp) is coupledovernight using one equivalent of HOBt in a 50% mixture of DMF andmethylene chloride. The amido group of Asn or Gln is protected by Xanwhen DCCI coupling is used instead of the active ester method. Alsocommonly used are BOC Asn or BOC Gln in the presence of 2 eq.N-hydroxybenzotriazole per equivalent of BOC-AA. Tos is used to protectthe guanido group of Arg and the imidazole group of His, and the sidechain carboxyl group of Asp and Glu is protected by OBzl. At the end ofthe synthesis, the following composition is obtained: X₁-Leu-Ala-Arg(X⁷)-Tyr(X²)-Tyr(X²)-Ser(X³)-Ala-Leu-Arg(X⁷)-His(X⁸)-Tyr(X²)-Ile-Asn(X⁶)-Leu-Ile-Thr(X³)-Arg(X⁷)-Gln(X⁶)-Arg(X⁷)-Tyr(X²)-MBHAresin; wherein X₁ is BOC, X₂ is DCB, X₃ is Bzl, X₆ is Xan, X₇ is Tos andX₈ is DNP. Xan may have been partially or totally removed by TFAtreatment used to deblock the alpha-amino protecting group.

In order to cleave and substantially deprotect the resulting protectedpeptide-resin, it is treated with 1.5 ml. anisole, and 30 ml. hydrogenfluoride(HF) per gram of peptide-resin, first at -20° C. for 20 min. andthen at 0° C. for 40 minutes. After elimination of the HF under highvacuum, the resin-peptide is washed with dry diethyl ether, and thepeptides are then extracted with water and separated from the resin byfiltration.

The cleaved peptide is then purified by reverse-phase HPLC and thenrechromatographed for final purification using preparative HPLC asdescribed in Rivier et al., Peptides: Structure and Biological Function(1979) pp. 125-128. The chromatographic fractions are carefullymonitored by HPLC, and only the fractions showing substantial purity arepooled.

EXAMPLE II

The peptide hNPY (17-36) having the formula:H-Met-Ala-Arg-Tyr-Tyr-Ser-Ala-Leu-Arg-His-Tyr-Ile-Asn-Leu-Ile-Thr-Arg-Gln-Arg-Tyr-NH₂is synthesized using the method as described in Example I.

EXAMPLE III

The peptide [Phe²⁷ ]-NPY (18-36) having the formula:H-Ala-Arg-Tyr-Tyr-Ser-Ala-Leu-Arg-His-Phe-Ile-Asn-Leu-Ile-Thr-Arg-Gln-Arg-Tyr-NH₂is synthesized using the method as described in Example I.

EXAMPLE IV

The peptide [Ac-D-Ala¹⁷ ]-NPY (17-36) having the formula:Ac-D-Ala-Ala-Arg-Tyr-Tyr-Ser-Ala-Leu-Arg-His-Tyr-Ile-Asn-Leu-Ile-Thr-Arg-Gln-Arg-Tyr-NH₂is synthesized using the general method as described in Example I, andthen reacting with acetic acid in the presence of DCC, or reacting withacetic anhydride, after deblocking the alpha-amino group on the finalD-Ala residue.

EXAMPLE V

The peptide NPY (19-36) having the formula:H-Arg-Tyr-Tyr-Ser-Ala-Leu-Arg-His-Tyr-Ile-Asn-Leu-Ile-Thr-Arg-Gln-Arg-Tyr-NH₂is synthesized using the method as described in Example I.

EXAMPLE VI

The peptide [Nle¹⁷ ]-NPY (17-36) having the formula:H-Nle-Ala-Arg-Tyr-Tyr-Ser-Ala-Leu-Arg-His-Tyr-Ile-Asn-Leu-Ile-Thr-Arg-Gln-Arg-Tyr-NH₂is synthesized using the method as described in Example I.

EXAMPLE VII

The peptide [D-Ser¹⁸ ]-NPY (18-36) having the formula:H-D-Ser-Arg-Tyr-Tyr-Ser-Ala-Leu-Arg-His-Tyr-Ile-Asn-Leu-Ile-Thr-Arg-Gln-Arg-Tyr-NH₂is synthesized using the method as described in Example I.

EXAMPLE VIII

The peptide [Ala¹⁷, His²¹ ]-NPY (17-36) having the formula:H-Ala-Ala-Arg-Tyr-His-Ser-Ala-Leu-Arg-His-Tyr-Ile-Asn-Leu-Ile-Thr-Arg-Gln-Arg-Tyr-NH₂is synthesized using the method as described in Example I.

EXAMPLE IX

The peptide [D-Ile¹⁸ ]-NPY (18-36) having the formula:D-Ile-Arg-Tyr-Tyr-Ser-Ala-Leu-Arg-His-Tyr-Ile-Asn-Leu-Ile-Thr-Arg-Gln-Arg-Tyr-NH₂is synthesized using the method as described in Example I.

EXAMPLE X

The peptide [Ac-Arg¹⁷ ]-NPY (17-36) having the formula:Ac-Arg-Ala-Arg-Tyr-Tyr-Ser-Ala-Leu-Arg-His-Tyr-Ile-Asn-Leu-Ile-Thr-Arg-Gln-Arg-Tyr-NH₂is synthesized using the general method as described in Example I, andthen reacting with acetic acid in the presence of DCC, or reacting withacetic anhydride, after deblocking the alpha-amino group on the finalresidue.

EXAMPLE XI

The peptide [Gln¹⁹ ]-NPY (19-36) having the formula:H-Gln-Tyr-Tyr-Ser-Ala-Leu-Arg-His-Tyr-Ile-Asn-Leu-Ile-Thr-Arg-Gln-Arg-Tyr-NH₂is synthesized using the method as described in Example I.

EXAMPLE XII

The peptide [Phe²⁰ -NpY (18-36) having the formulaH-Ala-Arg-Phe-Tyr-Ser-Ala-Leu-Arg-His-Tyr-Ile-Asn-Leu-Ile-Thr-Arg-Gln-Arg-Tyr-NH₂is synthesized using the method as described in Example I.

EXAMPLE XIII

The peptide [C^(a) MeLeu¹⁷ ]-pNPY (17-36) having the formula: H-C^(a)MeLeu-Ala-Arg-Tyr-Tyr-Ser-Ala-Leu-Arg-His-Tyr-Ile-Asn-Leu-Ile-Thr-Arg-Gln-Arg-Tyr-NH₂is synthesized using the method as described in Example I.

EXAMPLE XIV

The peptide [N^(a) MeLeu¹⁷ ]-pNPY (17-36) having the formula: H-N^(a)MeLeu-Ala-Arg-Tyr-Tyr-Ser-Ala-Leu-Arg-His-Tyr-Ile-Asn-Leu-Ile-Thr-Arg-Gln-Arg-Tyr-NH₂is synthesized using the method as described in Example I.

EXAMPLE XV

The peptide [desamino Ala¹⁸ ]-NpY (18-36) having the formula:desamino-Ala-Arg-Tyr-Tyr-Ser-Ala-Leu-Arg-His-Tyr-Ile-Asn-Leu-Ile-Thr-Arg-Gln-Arg-Tyr-NH₂ is synthesized using the method as described in Example I.

EXAMPLE XVI

The peptide [For-Ala¹⁸, Glu²³, Arg²⁶ ]-NPY (18-36) having the formula:For-Ala-Arg-Tyr-Tyr-Ser-Glu-Leu-Arg-Arg-Tyr-Ile-Asn-Leu-Ile-Thr-Arg-Gln-Arg-Tyr-NH₂is synthesized using the general method as described in Example I tocreate the peptide chain, and the BOC protecting group on the final Alaresidue is removed. The peptide-resin is then treated with 98% formicacid at 5°-15° C. and acetic anhydride is added dropwise, and thereaction mixture is stirred for 1 hour. After completion of thereaction, cleavage from the resin and of the protecting groups takesplace as set forth in Example I.

EXAMPLE XVII

The peptide [Nva¹⁷, Ala²¹, Leu²⁸ ]-NPY (17-36) having the formula:H-Nva-Ala-Arg-Tyr-Ala-Ser-Ala-Leu-Arg-His-Tyr-Leu-Asn-Leu-Ile-Thr-Arg-Gln-Arg-Tyr-NH₂is synthesized using the method as described in Example I.

EXAMPLE XVIII

The peptide [Thr²², Gln²³ ]-NPY (18-36) having the formula:H-Ala-Arg-Tyr-Tyr-Thr-Gln-Leu-Arg-His-Tyr-Ile-Asn-Leu-Ile-Thr-Arg-Gln-Arg-Tyr-NH₂is synthesized using the method as described in Example I.

EXAMPLE XIX

The peptide [desamino Leu¹⁷, Asn²³, Val³⁰ ]-NPY (17-36) having theformula: H-desaminoLeu-Ala-Arg-Tyr-Tyr-Ser-Asn-Leu-Arg-His-Tyr-Ile-Asn-Val-Ile-Thr-Arg-Gln-Arg-Tyr-NH₂is synthesized using the general method as described in Example I.

EXAMPLE XX

The peptide [Asp²², Ser²³, Thr³⁰ ]-NPY (18-36) having the formula:H-Ala-Arg-Tyr-Tyr-Asp-Ser-Leu-Arg-His-Tyr-Ile-Asn-Thr-Ile-Thr-Arg-Gln-Arg-Tyr-NH₂is synthesized using the method as described in Example I.

EXAMPLE XXI

The peptide [Gln²⁵, Leu³¹, Pro³⁴ ]-NPY (18-36) having the formula:H-Ala-Arg-Tyr-Tyr-Ser-Ala-Leu-Gln-His-Tyr-Ile-Asn-Leu-Leu-Thr-Arg-Pro-Arg-Tyr-NH₂is synthesized using the method as described in Example I.

EXAMPLE XXII

The peptide [Gln² Phe³⁶ ]-NPY (17-36) having the formula:H-Leu-Ala-Arg-Tyr-Tyr-Ser-Ala-Leu-Arg-Gln-Tyr-Arg-Asn-Leu-Ile-Thr-Arg-Gln-Arg-Phe-NH₂is synthesized using the method as described in Example I.

EXAMPLE XXVIII

The peptide [Phe³⁶ ]-pPYY (19-36) having the formula:H-Arg-Tyr-Tyr-Ala-Ser-Leu-Arg-His-Tyr-Leu-Asn-Leu-Val-Thr-Arg-Gln-Arg-Phe-NH₂is synthesized using the method as described in Example I.

EXAMPLE XXIV

The peptide pPYY (18-36) having the formula:H-Ser-Arg-Tyr-Tyr-Ala-Ser-Leu-Arg-His-Tyr-Leu-Asn-Leu-Val-Thr-Arg-Gln-Arg-Tyr-NH₂is synthesized using the method as described in Example I.

EXAMPLE XXV

The peptide [Ac-Ser.sup. 18,Phe²⁷ ]-pPYY (I8-36) having the formula:Ac-Ser-Arg-Tyr-Tyr-Ala-Ser-Leu-Arg-His-Phe-Leu-Asn-Leu-Val-Thr-Arg-Gln-Arg-Tyr-NH₂is synthesized using the general method as described in Example I, andthen reacting with acetic anhydride, after deblocking the alpha-aminogroup on the final Ser residue.

EXAMPLE XXVI

The peptide [Nle¹⁷, Asn²², Phe²⁷ ]-NPY (17-36) having the formula:H-Nle-Ala-Arg-Tyr-Tyr-Asn-Ala-Leu-Arg-His-Phe-Ile-Asn-Leu-Ile-Thr-Arg-Gln-Arg-Tyr-NH₂is synthesized using the method as described in Example I.

EXAMPLE XXVII

The peptide [D-Ala¹⁸, Glu²¹, His³⁴ ]-NPY (18-36) having the formula:H-D-Ala-Arg-Tyr-Glu-Ser-Ala-Leu-Arg-His-Tyr-Ile-Asn-Leu-Ile-Thr-Arg-His-Arg-Tyr-NH₂is synthesized using the method as described in Example I.

EXAMPLE XXVIII

The peptide [Bz-Leu¹⁷, Pro³⁴, Phe³⁶ ]-pNPY (17-36) having the formula:Bz-Leu-Ala-Arg-Tyr-Tyr-Ser-Ala-Leu-Arg-His-Tyr-Ile-Asn-Leu-Ile-Thr-Arg-Pro-Arg-Phe-NH₂is synthesized using the general method as described in Example I, andthen reacting with benzoic acid in the presence of DCC after removingthe BOC group on the final Leu residue.

EXAMPLE XXIX

The peptide [Lys¹⁹, Phe²⁷, Val²⁸ ]-NpY (18-36) having the formula:H-Ala-Lys-Tyr-Tyr-Ser-Ala-Leu-Arg-His-Phe-Val-Asn-Leu-Ile-Thr-Arg-Gln-Arg-Tyr-NH₂is synthesized using the method as described in Example I.

EXAMPLE XXX

The peptide [D-Ala¹⁷, Val²⁸, Phe³² ]-NPY (17-36) having the formula:D-Ala-Arg-Tyr-Tyr-Ser-Ala-Leu-Arg-His-Tyr-Val-Asn-Leu-Ile-Phe-Arg-Gln-Arg-Tyr-NH₂is synthesized using the general method as described in Example I, andthen reacting with acetic acid in the presence of DCC, or reacting withacetic anhydride, after deblocking the alpha-amino group on the finalD-Ala 10 residue.

EXAMPLE XXXI

The peptide [C^(a) MeSer¹⁸, Met³⁰, Phe³⁶ ]-NPY (18-36) having theformula: H-C^(a)MeSer-Tyr-Tyr-Ser-Ala-Leu-Arg-His-Tyr-Ile-Asn-Met-Ile-Thr-Arg-Gln-Arg-Phe-NH₂is synthesized using the method as described in Example I.

EXAMPLE XXXII

The peptide [Arg¹⁷, Ile¹⁸, Phe²⁷,36 ]-NPY (17-36) having the formula:H-Arg-Ile-Arg-Tyr-Tyr-Ser-Ala-Leu-Arg-His-Phe-Ile-Asn-Leu-Ile-Thr-Arg-Gln-Arg-Phe-NH₂is synthesized using the method as described in Example I.

EXAMPLE XXXIII

The peptide [Ser¹⁸, Phe²⁷ ]-pNPY (17-36) having the formula:H-Leu-Ser-Arg-Tyr-Tyr-Ser-Ala-Leu-Arg-His-Phe-Ile-Asn-Leu-Ile-Thr-Arg-Gln-Arg-Tyr-NH₂is synthesized using the method as described in Example I.

EXAMPLE XXXIV

The peptide [N^(a) MeIle¹⁸, Gln²⁵, Phe²⁷ ]-NPY (18-36) having theformula: N^(a)MeIle-Arg-Tyr-Tyr-Ser-Ala-Leu-Gln-His-Phe-Ile-Asn-Leu-Ile-Thr-Arg-Gln-Arg-Tyr-NH₂is synthesized using the general method as described in Example I.

EXAMPLE XXXV

The peptide [D-Ser¹⁸, Phe³⁶ ]-NPY (18-36) having the formula:H-D-Ser-Arg-Tyr-Tyr-Ser-Ala-Leu-Arg-His-Tyr-Ile-Asn-Leu-Ile-Thr-Arg-Gln-Arg-Phe-NH₂is synthesized using the method as described in Example I.

EXAMPLE XXXVI

The peptide [Asp²³, Arg²⁶ ]hNPY (17-36) having the formula:H-Met-Ala-Arg-Tyr-Tyr-Ser-Asp-Leu-Arg-Arg-Tyr-Ile-Asn-Leu-Ile-Thr-Arg-Gln-Arg-Tyr-NH₂is synthesized using the method as described in Example I.

EXAMPLE XXXVII

The peptide [Glu²³, Ile²⁹ ]-NPY (18-36) having the formula:H-Ala-Arg-Tyr-Tyr-Ser-Glu-Leu-Arg-His-Tyr-Ile-Ile-Leu-Ile-Thr-Arg-Gln-Arg-Tyr-NH₂is synthesized using the method as described in Example I.

EXAMPLE XXXVIII

The peptide [D-Ala¹⁷ ]-NPY(17-36)-OH having the formula:D-Ala-Ala-Arg-Tyr-Tyr-Ser-Ala-Leu-Arg-His-Tyr-Ile-Asn-Leu-Ile-Thr-Arg-Gln-Arg-Tyr-OHis synthesized on a chloromethylated resin using the general method asdescribed in Chemistry Letters. K. Horiki et al., 165-168 (1978).

The synthetic NPY analogs are tested for their effect on mean arterialblood pressure (MAP) in conscious rats. Saline solutions of the peptidesare injected intra-arterially into conscious rats, and arterial pressureis monitored via an indwelling femoral cannula directly coupled to apressure transducer. MAP is calculated as[(systolic-diastolic/3)+diastolic] and is determined 1 minute afteradministration of the peptide. Control animals receive saline vehiclealone.

pNpY (17-36), NpY (18-36) and NPY (19-36) significantly decrease MAP atfive and ten minutes after administration. The maximal response is seenwith NPY (18-36), which produces a fall in MAP from 102±2 mmHg to 50±6mmHg after five minutes. All fragments increase heart rate (HR) afterinjection when compared to the control group. There is no significantdifference in the maximal HR obtained between any of the fragments.

NPY (18-36) decreases MAP in a dose-dependent manner. At five minutesafter injection, there is no significant change in MAP in the group thatreceived 10 μg, however, there is a significant decrease in MAP in the30 μg group and a more pronounced effect in the groups that receive 100and 300 μg. There is no significant difference in the decrease in MAPobtained after administration of 100 or 300 μg. All doses producemaximal decrease in MAP five minutes after administration, except forthe 10 μg dose which has a nadir MAP at t=15 min. Heart rates are onlysignificantly increased in the 30 μg group.

NPY is given to a group of animals that are pretreated with NPY (18-36)to determine if the hypotension seen after NPY (18-36) administration isdue to antagonism of the hypertensive actions of NPY. The increase inMAP (Δ MAP) obtained by NPY administration (1 μg, intra-arterially) toanimals pretreated with NPY (18-36) (300 μg) is not significantlydifferent from that obtained after NPY administration to control animals(28 ±5 mmHg vs 32±5 mmHg, respectively, with 3 animals for each test).

pNPY transiently elevates intracellular Ca++ concentrations with an EC₅₀of 2.0 nM. Maximal Ca++ increases are 200-550 nM above basal levels(40-70 nM). NPY (18-36) (100 nM) increases Ca++ less than 10% as much asdoes an equal concentration of NPY, indicating that NPY (18-36) is onlya very weak agonist in this system. Moreover, NPY (18-36) does notantagonize the Ca++ mobilization by NPY; after addition of 100 nM NPY(18-36), 100 nM NPY still elevates intracellular Ca++ to the same extentas under control conditions. Furthermore, pNPY (18-36) neither inhibitscAMP formation nor antagonizes NPY-mediated inhibition.

NPY analogs or nontoxic addition salts thereof, combined with apharmaceutically acceptable carrier to form a pharmaceuticalcomposition, may be administered to mammals, including humans, eitherintravenously, subcutaneously, intramuscularly, percutaneously, e.g.intranasally, intracerebrospinally, orally or by suppository. Thepeptide should be at least about 90% pure and preferably should have apurity of at least about 98% when administered to humans. This puritymeans that the intended peptide constitutes the stated weight % of alllike peptides and peptide fragments present. Administration may beemployed by a physician to lower blood pressure to counteracthypertension; the required dosage will vary with the particularcondition being treated, with the severity of the condition and with theduration of desired treatment.

Such peptides are often administered in the form of pharmaceuticallyacceptable nontoxic salts, such as acid addition salts or metalcomplexes, e.g., with zinc, iron, calcium, barium, magnesium, aluminumor the like (which are considered as addition salts for purposes of thisapplication). Illustrative of such acid addition salts arehydrochloride, hydrobromide, sulphate, phosphate, tannate, oxalate,fumarate, gluconate, alginate, maleate, acetate, citrate, benzoate,succinate, malate, ascorbate, tartrate and the like. If the activeingredient is to be administered in tablet form, the tablet may containa binder, such as tragacanth, corn starch or gelatin; a disintegratingagent, such as alginic acid; and a lubricant, such as magnesiumstearate. If administration in liquid form is desired, sweetening and/orflavoring may be used, and intravenous administration in isotonicsaline, phosphate buffer solutions or the like may be effected.

The peptides should be administered under the guidance of a physician,and pharmaceutical compositions will usually contain the peptide inconjunction with a conventional, pharmaceutically-acceptable carrier.Usually, the dosage will be from about 1 to about 200 micrograms of thepeptide per kilogram of the body weight of the host. As used herein alltemperatures are °C. and all ratios are by volume. Percentages of liquidmaterials are also by volume.

Although the invention has been described with regard to its preferredembodiments, which constitute the best mode presently known to theinventors, it should be understood that various changes andmodifications as would be obvious to one having the ordinary skill inthis art may be made without departing from the scope of the inventionwhich is set forth in the claims appended hereto.

Various features of the invention are emphasized in the claims whichfollow.

What is claimed is:
 1. A synthetic peptide having the formula: X-Q-R₁₉-R₂₀ -R₂₁ -R₂₂ -R₂₃ -Leu-R₂₅ -R₂₆ -R₂₇ -R₂₈ -R₂₉ -R₃₀ -R₃₁ -R₃₂ -Arg-R₃₄-Arg-R₃₆ -Y wherein X is H or C^(a) Me or N^(a) Me or desamino or anacyl group having 7 carbon atoms or less; Q is R₁₇ -R₁₈, R₁₈ or desQ;R₁₇ is Met, Arg, Nle, Nva, Leu, Ala or D-Ala; R₁₈ is Ala, Ser, Ile,D-Ala, D-Ser or D-Ile; R₁₉ is Arg, Lys or Gln; R₂₀ is Tyr or Phe; R₂₁ isTyr, Glu, His or Ala; R₂₂ is Ser, Ala, Thr, Asn or Asp; R₂₃ is Ala, Asp,Glu, Gln, Asn or Ser; R₂₅ is Arg or Gln; R₂₆ is His, Arg or Gln; R₂₇ isPhe or Tyr; R₂₈ is Ile, Leu, Val or Arg; R₂₉ is Asn or Ile; R₃₀ is Leu,Met, Thr or Val; R₃₁ is Ile, Val or Leu; R₃₂ is Thr or Phe; R₃₄ is Gln,Pro or His; R₃₆ is Phe or Tyr; and Y is NH₂ or OH; provided that when Qis R₁₈, then at least one of R₂₇ and R₃₆ is Phe.
 2. The peptide of claim1 wherein Q is R₁₈.
 3. The peptide of claim 2 wherein R₂₇ is Phe.
 4. Thepeptide of claim 2 wherein R₃₆ is Phe.
 5. The peptide of claim 4 whereinR₂₇ is Phe.
 6. The peptide of claim 5 wherein R₁₈ is Ala.
 7. The peptideof claim 5 wherein R₁₈ is D-Ala.
 8. The peptide of claim 5 wherein R₁₈is D-Ser.
 9. The peptide of claim 5 wherein R₁₈ is D-Ile.
 10. Thepeptide of claim 9 wherein R₂₀ is Tyr.
 11. A pharmaceutical compositionfor lowering blood pressure comprising an effective amount of a peptideas set forth in claim 1 or a nontoxic salt thereof, and apharmaceutically acceptable liquid or solid carrier therefor.
 12. Amethod for lowering the blood pressure of a mammal, which methodcomprises administering to said mammal an effective amount of asynthetic peptide or a nontoxic salt thereof, having the formula:X-Q-R₂₀ -R₂₀ -R₂₁ -R₂₂ -R₂₃ -Leu-R₂₅ -R₂₆ -R₂₇ -R₂₈ -R₂₉ -R₃₀ -R₃₁ R₃₂-Arg-R₃₄ -Arg-R₃₆ -Y wherein X is H or C^(a) Me or N^(a) Me or desaminoor an acyl group having 7 carbon atoms or less; Q is R₁₇ -R₁₈, R₁₈, R₁₉or desQ; R₁₇ is Met, Nle, Nva, Arg, Leu, Ala or D-Ala; R₁₈ is Ala, Ser,Ile, D-Ala, D-Ser or D-Ile; R₁₉ is Arg, Lys or Gln; R₂₀ is Tyr or Phe;R₂₁ is Tyr, Glu, His or Ala; R₂₂ is Ser, Ala, Thr, Asn or Asp; R₂₃ isAla, Asp, Glu, Gln, Asn or Ser; R₂₅ is Arg or Gln; R₂₆ is His, Arg orGln; R₂₇ is Phe or Tyr; R₂₈ is Ile, Leu, Val or Arg; R₂₉ is Asn or Ile;R₃₀ is Leu, Met, Thr or Val; R₃₁ is Ile, Val or Leu; R₃₂ is Thr or Phe;R₃₄ is Gln, Pro or His; R₃₆ is Phe or Tyr; and Y is NH₂ or OH.
 13. Themethod in accordance with claim 12 wherein said administering is carriedout either orally, intravenously, subcutaneously, percutaneously,intracerebrospinally, intramuscularly or by suppository.
 14. The methodof claim 13 wherein said administration is at a level of between about 1and about 200 micrograms per Kg. of body weight.
 15. The method of claim14 wherein said peptide has the formula:H-Ala-Arg-Tyr-Tyr-Ser-Ala-Leu-Arg-His-Phe-Ile-Asn-Leu-Ile-Thr-Arg-Gln-Arg-Phe-NH₂.16. A synthetic peptide having the formula: X-R₁₇ -R₁₈-Arg-Tyr-Ser-Ala-Leu-Arg-His-R₂₇ -Ile-Asn-Leu-Ile-Thr-Arg-Gln-Arg-R₃₆-NH₂, wherein X is H or C^(a) Me or N^(a) Me or desamino or an acylgroup having 7 carbon atoms or less; R₁₇ is Arg or Leu; R₁₈ is Ala orIle or Ser; R₂₇ is Phe or Tyr; and R₃₆ is Phe or Tyr.
 17. The peptide ofclaim 16 wherein X is H.
 18. The peptide of claim 17 wherein R₂₇ and R₃₆are Tyr.
 19. A synthetic peptide having the formula: X-R₁₈-Arg-Tyr-Tyr-Ala-Ser-Leu-R₂₅ -His-R₂₇-Leu-Asn-Leu-Val-Thr-Arg-Gln-Arg-R₃₆ -NH₂, wherein X is H or C.sup. Meor N^(a) Me or desamino or an acyl group having 7 carbon atoms or less;R₁₈ is Ala or Ser; R₂₅ is Arg or Gln; R₂₇ is Phe or Tyr; and R₃₆ is Pheor Tyr.
 20. The peptide of claim 19 wherein R₂₇ and R₃₆ are Tyr.